high GRR caused by CFH variant: the presence of two risk alleles in an individual increased risk of developing AMD by a factor of 7.4 [101]. On the other hand, in order to detect alleles with modest effect sizes, tens of thousands of cases and controls could be needed, as demonstrated by studies on human height variation with a combined sample size of ~63,000 individuals [102–104]. These studies found 54 variants, each with an average size effect of 0.4 cm per allele, indicating that an even larger sample size maybe needed to detect common, small-effect alleles responsible for the residual population variance [105].
